1. Field of the Invention
The present invention relates to a measuring car arrangement for monitoring an existing track position with respect to a desired track position, the track comprising two rails having rail heads, which comprises a measuring car having a frame extending longitudinally in a plane and undercarriages supporting the frame for mobility in an operating direction and having wheels, the wheels having contact points with the rail heads and the contact points defining a reference plane, the frame plane extending parallel to the reference plane, and a satellite bogie transportable on the measuring car frame and being drivable along the track independently of the measuring car.
2. Description of the Prior Art
Such a measuring car arrangement has been disclosed in the prospectus "EM SAT Geometerwagen" of Plasser & Theurer, of Vienna, Austria. In this arrangement, a large operator's cab and a powerful drive are arranged above the plane of the machine frame. A satellite measuring bogie is connected to a laser beam emitter and is connectable to the machine frame below the frame plane for a common transit of the machine and satellite bogie between operating sites. This fully electronic recording car with a self-propelled laser satellite produces accurate track geometry corresponding to the target position of the track by measuring the actual position of the track before operation of the work machine (for reasons of greater accuracy this measurement is done using a Laser reference chord 40-300 m long); calculating the displacement value from the actual position by comparing it with the target position of the track; and supplying the work machine with this data, which also directs the machine.
U.S. Pat. No. 4,691,565, dated Sep. 8, 1987, discloses a mobile machine for measuring and recording track parameters and/or for correcting a track position, including a satellite bogie preceding the machine in an uncorrected section of the track. The self-propelled satellite bogie is equipped with a laser beam emitter and, for common transit with the machine, the satellite bogie may be driven onto the machine over a ramp pivoted to a front end of the machine frame. The machine is a track measuring car and its forward end carries a laser beam receiver and various devices for monitoring and storing track position correction values.
An article entitled "Leistungsfahige Oberbaumaschinen fur moderne Gleise" (High-performance track maintenance machines for modern tracks) in "Eisenbahntechnische Rundschau" 39 (1990), No. 4, pp. 201-211, points out at 2.2 that track tamping operations must be preceded by costly measuring and processing operations monitoring the existing track position for obtaining the correction values for the desired track geometry. The article states that tests for automating such operations were undertaken with an EM-SAT measuring machine. A laser beam is used as reference chord between a satellite bogie located at a fixed track point and a measuring car continuously moving towards the satellite bogie, and the height of the arch above the reference chord is measured, the measured parameter is digitalized and the digital value is stored in a computer. Additional measurements of the lateral distances from the fixed points enable the differences between the existing and a desired track position to be monitored so that the correction values may be computed and used as input for a computer on a track lining and leveling machine for controlling the lining and/or leveling of the track. This work can be done more rapidly, more economically and protected from train traffic on a neighboring track with a track geometry car GM 80 constituted by a unit which is 17 m long and weighs 30 t, and which may be separated at an operating site into emitter and receiver parts.